donkey's years

US /ˈdɑŋ.kiz jɪərz/

UK /ˈdɑŋ.kiz jɪərz/

1.

a very long time

:

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I haven't seen him in donkey's years.

•

It's been donkey's years since we last went on holiday.

:

donkey year year-round leap year academic year fiscal year half year